Coated fabricated metallic sheet



Aug. 20,- 1940. H. KOH LI IR 2,212,271

COATED FABRICATED METALLIC SHEET Filed Marc]; 20, 1959 SHEET STEELTIN-ZINC MERCUR Y AMALGAM COA TING SHEET STEEL 7 zuvc co ATlNs AMALGAMCOATING F: g. 2

INVENTOR Henry L..Kohler TTORNEY Patented Aug. 20, 1940 UNITED STATESCOATED FABRICATED METALIJC SHEET Henry L. Kohler, Kansas City, Mo.,assignor to Andrew A. Kramer, Kansas City, Mo.

Application March 20, 1939', Serial No. 262,966

A 11 Claims. (01. 29-181) My invention relates to protective coatedarticles, and more particularly to coated fabricated metallic sheets, orsheet metal articles provided with a protective coating. Thisapplication is a continuation in part of my co-pending applicationSerial No. 160,803, filed August 25, 1937.

A difiiculty that has always existed in the util ization of galvanizedmetallic sheets for making certain articles out of the same, has beenthat the galvanizing coating is not suiliciently resistant to corrosionunder certain ,conditions to make the practical use thereof possible. Anattempt to overcome this difliculty has been made by providing a heaviergalvanizing coating on the sheet.

The heavy'zinc coating thus provided, however, has the disadvantagethat, when the sheet is bent, the coating at the bend would crack andtend to peel or flake ofi. As a result, although the sheet as a wholewas provided with a heavy 2o galvanizing coating over its entire surfacebefore being fabricated, the bending of a sheet to form a flange or aseam thereon, frequently damaged the galvanizing coating on the sheet soseriously that it would render the coating partially ineffec- 5 tive, onthe outside of the bends required to form the flanges, or seams.Consequently the advantage of the heavy galvanizing coating on the sheetwas largely lost, this being true because, at the point at which thegalvanizing coating was caused to be damaged, or ruptured, by bending,

the sheet would be, for practical purposes, no better than an uncoatedsheet, as far as resistance to oxidization, or other corrosion, wasconcerned. While many attempts have been made to overcome thisdifliculty, as by a hot dipping process after the article has beenformed from the galvanized sheet, for example, this is' ditficult toaccomplish and requires expensive equipment, if any large sheet metalarticle is to be galvanized after fabrication by such a dipping process.

' It is a purpose of my invention to provide means for overcoming theabove mentioned difliculty with galvanized sheets that have a heavycoating of galvanizing thereon, providing a pro- 4 tective coating atthe bend, or bends, in the fabricated sheet that will be even moreresistant to corrosion, due to certain causes, than the galvanized sheetwas priorto bending, and which will resist every kind of corrosion atleast as well as did the galvanized sheet with the heavy galvanizingcoating thereon prior to its fabrication, and also to provide a sheetthatis much more resistant to corrosion over the entire area thereof, ifsuch resistance over such entire area is desired,

than is possible with ordinary zinc coatings provided by the usualgalvanizing process. I preferably accomplish this by providing atin-zincmercury amalgam coating on the sheet, which is applied to thearea thereof that it is desired to give the better protection than canbe given by 5 means of the heavy galvanizing coating usually provided.

My improved protective coating may be uti-. lized to give betterprotection than zinc against certain types of corrosion, or corrosiondue to 10 certain causes, either over the entire area of a metallicsheet, or over the entire area of one side thereof, or over the entirearea of a fabricated sheet metal section, or one side of such a section,if this should be desired, and is par- 15 ticularly adapted for use atand adjacent the bends in a fabrication sheet, whereby any rupture inthe galvanizing coating that may have occurred during fabrication, fromany of the fabrication steps, will be closed and the sheet protected atsuch bends, or other fabricated portions thereof, more effectively thanwas the case before the bending, or other operation, thereon, thatdamaged, or ruptured, the protective zinc coating on the sheetoriginally. 25

In galvanizing iron, or steel, the zinc forms a thin layer of ferrouszinc alloy immediately adjacent the steel or iron of the sheet, whichhas a much higher melting point than the spelter, or I, zinc, andimmediately sets and thus prevents any 30 further alloying actionbetween the zinc and the. iron of the steel. The remainder of thespelter forms a coating of almost pure zinc overlying the coating offerrous zinc alloy on the sheet. This outer coating of zinc varies inthickness consid- 35 erably, depending on how it is applied to thesheet. Sheets are provided with a heavy coating of galvanizing byrepeatedly dipping, or running the sheets through the galvanizing bath.This zinc coating does not have the tensile strength of steel, nor theflexibility of steel, and consequently when the sheet is bent thetendency is for the coating, particularly on the outer side of the bendin the sheet, to rupture, or crack, at least down to the ferrous zincalloy that forms the innermost coating on the sheet. If nothing is doneto rectify the rupture in the zinc coating after fabrication, such aheavy coated, or heavy galvanized sheet, will be subject tosubstantially as much corrosion at such ruptured point in the 50 coatingas would be true if it had never been coated at that point. My inventionentirely overcomesthis difiiculty and makes the bend, even though arupture had occurred in the galvanizing coating in the fabrication ofthe sheet, more resistant to corrosion than was the case prior tofabrication, and particularly resistant to corrosion due to sulphurcompounds present in certain oils and similar materials that may beconfined in tanks that are manufactured out of galvanto fabrication ofthe sheet. Mercury may be re garded as semi-noble. metal, and isparticularly resistant to corrosion, because it is not soluble in dilutesulphuric acid, hydrogen sulphide does not affect it as readily as itdoes zinc, and the amalgams of mercury take on the characteristics ofmercury to the extent that these are also highly resistant to corrosion,particularly'to corrosion due to acids, such as dilute sulphuric acid,or other acids and compounds, that may be encountered in the use offabricated galvanized sheets.

The mercury may be applied in the metallic form, but inasmuch as somedifficulty is .encountered .in preventing loss of mercury because of itsextremely mobile character, it is preferred that an amalgam be made ofmercury with zinc,

tin, bismuth, lead, or any metal that freely dissolves in mercury, whichis applied to the part to beprotected. Preferably, an amalgam of theconsistency of putty is rubbed on the metal at the place where the sameis to be protected, such as at a ruptured place in the coating on thesheet, which permits the excess to be removed with a cloth and thussaved for futureuse. It is.

of course, necessary to remove the zinc oxide,

the sheet, as obtained by the usual galvanizing process. Galvanizedmetallic sheets have a characteristic Spangled appearance. It is-highlydesirable to maintain this spangled appearance of the sheets after myimproved coating has.

been placed thereon. This is accomplished by utilizing a paste-likeamalgam of mercury and a metal that readily amalgamates with mercury.

such as tin, which is applied to the sheet in a manner that thestructural characteristics of the coating on .thesheet are not changed.Thus my invention provides a sheet that has substantially the sameappearance as an ordinary galvanized sheet, but which will, afterfabrication, have at least as good a protective coating thereon as ithad before fabrication, and in most cases, a better protective coating.As the term -fabricati0n is used herein, it means any bending, cutting,or punching operation, or any other operation on the sheet, that may beperformed thereon after the same has been rolled and galvanized.

It is a further purpose of my invention to provide a coating that willbe substantially of the same hardness as the zinc coating usuallyprovided on a sheet that is galvanized, this being accomplished by usingthe paste-like amalgam of such a composition and applied in such amanner that the amount of zinc and other metal, such as tin, in thefinal coating, will be such that it will have the desired hardness, eventhough the mercury is present therein. The presence of the mercury,however, gives the coating an extraordinarily greater amount ofresistance to corrosion, due to the fact that the mercury contentextends from the exposed surface 10 of .the coating inwardly toward andsubstantially to the metal forming the body of the sheet. Due to thepresence of the mercury at the surface that is exposed to corrosion, anycorrosive action that results due to sulphur compounds, or 15 anysimilar corrosive materials, that may come in contact with the surface.having my improved coating provided thereon, will result in the mercurybeing brought to the surface that is exposed in such quantity relativeto the other ingredients of the coating composition, that the corrosiveaction will be effectively stopped. Thus the zinc in the coating at theexposed surface would be attacked to a certain extent by certain acidsand sulphur compounds and would go into solution in the liquid that isin the tank, or other container, for which the sheets coated inaccordance with my invention are particularly useful. However, when thisoccurs, the mercury content in the exposed surface portion of thecoating becomes muchgreater in proportion to the other ingredientstherein after the zinc is dissolved, and as the mercury will not go intosolution, it forms a protective film over the exposedsurface, whichstops any further corrosive action. While the tendency of the amalgamthat is applied to produce thedesired coating is to penetrate the entirezinc coating of the sheet down to the steel, or to the ferrous zincalloy coating next to the steel of the sheet, and appears to do this inall cases, yet even if such were not -the case, substantially the sameresult would be obtained, as the surfacethat is outermost and which isexposed to'the corrosive action does contain, for example, in the casewhere a tin-mercury amalgam is used, zinc, tin and mercury in suchproportions that the mercury will produce the protective film as soon aseven very slight loss of zinc occurs, and the tin being more resistantto corrosion than the zinc, not be lost, but will remain with themercury at the exposed surface of the sheet. This protective film is, ofcourse, very thin and the major portion of the coating will continue toexist as a tin-zincmercury amalgam coating, even though this protectivefilm isformed.

Other objects and advantages of my invention will appear as thedescription of the drawing proceeds. I desire to have it understood,however, that I do not intend to limit myself to the particular detailsshown or described, except as defined in the claims.

In the drawing:

Fig. 1 is a fragmentary sectional view on a greatly enlarged scale,showing my improved amalgam coating applied to a sheet having a bendtherein, and

Fig. 2 is a similar view, showing my'improved amalgam coating applied toa sheet otherwise fabricated than by bending.

and 2 the metallic body portion of the sheet is indicated by the numeral3. The sheet shown in Fig. 1 is bent at 4 and the bend may cause damageto the coating of the sheet on the outer side 70 Referring in detail tothe drawing, in Figs. 1

thereof. The zinc coating provided on the sheet is indicated by thenumeral and the amalgam coating around the outside of the bend in thesheet is indicated in Fig. 1 by the numeral 6.

In Fig. 2 the same numerals are applied to the zinc coating and theamalgam coating, but instead of showing a sheet with a bend therein, thesheet is shown as being fabricated bypunching a hole I therein, thisbeing merely illustrative of some fabrication operation that may beperformed on the sheet.

My improved protective coating is provided on galvanized sheets thathave been fabricated to the desired size and shape, by bending,die-shaping, cutting and punching operations, or any of these that maybe necessary to produce the article, or sections of an article, of thedesired shape from the galvanized sheet of metal. After the sheet hasbeen fabricated, it is cleaned at the places at which the protectivecoating is to be provided thereon, usually by means of dilutehydrochloric acid, or a solution of tin chloride, or antimony chloride,or lead chloride, or zinc chloride, or cyanide of soda. This cleaningsolution may be applied with a brush or swab of some character, and theexcess may be removed with a cloth, or any other suitable means. When itis desired to apply the protective coating only at or adjacent aruptured area on a galvanized sheet, or an area that may have beendamaged to the extent of injuring the protective coating, or rupturingthe same, the galvanized sheets are cleaned only on the outer sides ofall bends therein, or any other area at which the coating may have beenruptured, or damaged, and areas adjacent these bends, or other areaswhere the damage may have occurred. A zone at the place at which therupture in' the zinc coating may exist will thus be cleaned, and also azone on each side thereof.

The mercury is then applied to the cleaned zone at the ruptured place inthe coating and adjacent thereto, and in case metallic mercury is used,great care must be utilized to use only a small amount of the metal andto spread it by brushing, or otherwise-over a'large area of the cleansurface of the sheet, so as to prevent any material loss of mercury' dueto its rolling off the sheet because of its great mobility. The mercury,in being brushed over the sheet, particularly at the ruptured place, orzone, in the zinc coating will amalgamate with the zinc, forming a thincoating of mercury-zinc amalgam over the entire surface that has beencleaned,

with which the mercury comes in contact. At the rupture it will combinewith the zinc that is broken away from the sheet, forming an amalgamtherewith, which will adhere to the sheet closely and make a smoothcoating, entirely closing up the break, or rupture, in the galvanizedcoating. If the right quantity of mercury is used, the amalgam thusformed will be somewhat moist at first and can be rubbed off with thefingers to a certain extent, but will gradually harden, and afterseveral days, the sheet at the bend at which the mercury is applied,will have substantially the same appearance as the -remainder of thesheet and the amalgam will not rub off, even though the coating may berubbed persistently for a considerable period of time. The coating thusformed will not be soluble in dilute sulphuric acid, nor in any otherdilute acids, being only soluble in hot, concentrated sulv phuric acid.

As dilute sulphuric acid is ordinarily formed in oil tanks in which oilsare stored that have a large sulphur content, my invention isparticularly valuable for use in oil tanks that are made for the storageof such oils, which are commonly known as sour oils. Also many oils giveoff hydrogen sulphide, and in a moist atmosphere the sulphides of themetals are formed by the action of hydrogen sulphide on the metals..Thus the zinc coating on a sheet in an atmosphere in which hydrogensulphide and moisture is present, as will be the casein many tanks,particularly oil tanks, will be subjected to the combined action of thehydrogen sulphide and moisture, and transformed into a sulphide of zinc,which is readily soluble in dilute sulphuric acid. Where the zinccoating is ruptured, iron will be exposed and a sulphide of iron will beformed in a similar manner, by the action of hydrogen sulphide and moistair. On the other hand, sulphides of mercury, lead, tin and bismuth donot dissolve in dilute sulphuric acid. Also zinc and iron sulphidesoxidize rapidly in moist air to form sulphates. Sulphides of mercury arefairly stable, and thus form a protective coating for the zinc. Anamalgam of zinc and mercury will have largely the characteristics of themercury, particularly as to its solubility, audits tendency to be actedon by dilute sulphuric acid and oxygen. It will thus be seen that byproviding the amalgam of zinc with the mercury-in the manner abovereferred to, the sheet will be more resistant to corrosion, such asmight occur in the use of fabricated galvanized sheets in commercialuses, such as the making of tanks, as, not only will the zinc coating bemade more protective by the amalgamation with mercury, but the rupturedportion will be made more resistant to corrosion than was the case priorto bending of the sheet, when the zinc galvanizing coating wasundamaged. As a matter of fact, tests made on galvanized sheets providedwith my improved protective coating, utilizing the amalgamation ofmercury with the zinc to produce the same, show that the portion of thesheet that is not ruptured and that has not been treated, but which hasthe full thickness of galvanizing coating thereon, will be attacked bydilute sulphuric acid and other means causing corrosion, whereas, theamalgam coated portion of the sheet will not in any manner be affectedby'such corroding agents as would ordinarily occur in practice.

Instead of using 'metallic mercury, the amalgam coating can be formedwith mercury amalgams. When a mercury amalgam is used, the cleaning stepis carried out just as previously described, and after the cleaning ofthe area that is to be provided with the amalgam coating is completed,the mercury in the form of an amalgam, is applied. Preferably, theamalgam is made of the consistency of putty, so that it can be rubbed onthe metal with substantially no loss of mercury. When this is done, theexcess can be removed with a. cloth and saved for application to anothersheet, or another portion of the sheet. Amalgams of mercury with zinc,or with tin, or with bismuth, or with lead, or with any metal thatfreely dissolves in mercury, can be used to make this putty orpaste-like amalgam. Preferably, a tin-mercury amalgam is used to producea sheet that has a tin-zinc-mercury protective coating thereon.

A putty-like amalgam of mercury and a metal readily dissolving therein,oramalgamatingtherewith, such as tin, is made up prior to cleaning thesheets, or is made up in quantity, to be used whenever necessary, saidamalgam having such proportions of the metal, such as tin, and mercurytherein, as to produce a, soft putty-like material I of a consistency ofthick paste, or cream. The

proportions of mercury and the other metal amalgamating therewith thatare used to produce this soft putty-like coating material, will varywith the metals used and with the atmospheric temperature existing, asthe material must, of course, be of the soft, creamy putty-likecharacter at the temperature at which it is applied to the sheet. Thusin the winter time, when a lower temperature is encountered, both in theat-y part by weight of tin to two parts by weight of mercury, and that,if exceedingly low temperatures are encountered, even one part by weightof tin to three parts by weight of mercury are desirable. The relativeproportions of the metal amalgamating with the mercury that have to beutilized, are dependent upon the melting points of the metals that areamalgamated with the mercury, and the temperature encountered; Thus, ifthe mercury is heated, when the tin is added thereto, as much asfifty-five per cent tin can be included in the putty-like amalgam.

In making up the putty-like, or creamy, pastelike amalgam, it isnecessary that the metal that is to be dissolved in the mercury, oramalgamated therewith, is in a finely divided condition when it is to beamalgamated with the mercury. The tin, or similar metal, can be in theform of ,any small particles, such as shavings, turnings, cuttings, orin the form of a powder or granules. The finely divided tin, or similarmetal, is stirred into the quantity of mercury that is to be utilized tomake the amalgam in the proportions necessary substantially within thelimits above referred to. At ordinary room temperatures, it isunnecessary to heat the mercury to cause the tin to be dissolved, unlessa relatively large quantity of tin is to be incorporated in the amalgam.After a thorough stirring of the finely divided tin in the mercury, theamalgam is formed. However, if

low temperatures are encountered, at which themercury will have a moresluggish character, and f at which the amalgamation will not as readilyoccur, or in case it is desired to speed up the amalgamation of themercury and the tin, or similar metal, or increase the proportion of tinto be included in the putty, above that readily amalgamating with themercury at room temperature, the mercury may be heated for this purpose,keeping the temperature of the mercury well below that at which it wouldvaporize.

The soft-putty-like amalgam of tin and mercury produced as referred toabove, is applied to the cleaned area, or zone, of the galvanized sheet,by brushing or rubbing the same onto the cleaned area of the sheet witha cloth, or similar in her, this rubbing or brushing operation spreadr gthe tin-mercury amalgam over the cleaned area of the sheet and causing athin layer thereof to adhere to the outer surface oflthe zinc coating onthe sheet, and in case there is a rupture or damaged area in the sheet,from which the zinc has been entirely, or substantially entirely, re-

the sheet at this point also. As soon as the tinmercury amalgam contactsthe zinc coating on the sheet, it begins to react therewith to amalgamate the zinc in the zinc coating with some of the mercury in thetin-mercury amalgam. Accordingly, in brushing the amalgam back and forthover the ruptured area, some of the zinc of the galvanizing coating willbe caused to be spread over the ruptured area, and any loose flakes orparticles of zinc will be dissolved in the tin-mercury amalgam,amalgamating with the mercury therein.

The action between the zinc and the tin-mercury amalgam will-continueuntil the tin-mercury amalgam has penetrated the entire zinc coating ofthe sheet down to, at least, the ferrous zinc alloy at the surface ofthe iron or steel of the sheet. After the zinc is amalgamated with themercury, the resulting amalgam that is produced will gradually becomestiffer and harder, as the greater the amount of other metal amalgamatedwith the mercury; the harder or stifier the amalgam will become. As aresult, the penetration of the zinc by the mercury-tin amalgam willeventually produce a zinc-tin-mercury amalgam protective coating on thesheet over the entire surface to which the tin-mercury amalgam has beenapplied, which has lost the soft character of the tin-mercury amalgamand will become as hard as the zinc coating originally on the sheet.

Thus'the amalgam, when first placed on the .sheet treated in the abovemanner, will be soft enough that it can be rubbed off on the fingers toa certain extent, and after at least twenty-four hours the coating atthe area to which the amalgam has been applied will be hard enough thatnone of the same will rub off and the sheet can be handled without anydamage to the amalgam coating, just as readily as was the case with thezinc coating originally on the sheet. Also, after several days the sheetwill have substantially the same appearance as it did before any amalgamwas applied thereto, and none of the coating can be rubbed off, eventhough it may be rubbed persistently for a considerable period of time.The action of dilute sulphuric acid and other dilute acids, on the zincand tin will be retarded to such an'extent that the amalgamatedgalvanized sheet produced by my method, can be successfully used wherean ordinary galvanized sheet would have such a short life that its usewould be impractical.

While my improved coating is particularly adapted for use to preventcorrosion at ruptures or other sulphur compounds, which are ordinarilyfound in oil tanks, or similar receptacles. These sulphur compoundscause a corrosive action on the zinc coating of the'sheet as ordinarilyprovided in oil and similar tanks. However, by utilizing my protectivecoating, including the tinmercury amalgam, and applying it to the innermoved, the tin-mercury amalgam will adhere to surface of an oil tank, orthe sections of an oil tank, made up of sheets that have been bent, cutand punched, this undesirable corrosive, action is avoided entirely.

The tendency of the sulphur compounds, when acting on thezinc-tin-mercury amalgam coating, is to cause the mercury in the amalgamto form a protective film on the surface that is exposed to the actionof the dilute sulphuric acid, or hydrogen sulphide, or other sulphurcompounds, this causing some slight loss of some of the other metalsfrom the coating, such as the zinc and tin, but the mercury arrestingthis loss substantially immediately, due to the film forming action thatit has.

There is substantially no loss of mercury in the carrying out of mymethod, because, if there is any excess of amalgam applied to the sheet,such excess can be removed with a cloth, such as the cloth by means ofwhich the putty-like amalgam has been rubbed on the sheet, and the partthus removed saved for use on another sheet or other portion of thesheet. While it is immaterial whether the amalgam coating is of the samecomposition throughout, it has been found that if the soft putty-liketin-mercury amalgam, above referred to, is utilized, some of themercury'in the tin-mercury amalgam will amalgamate with the zincimmediately, forming a zinc-tin-mercury amalgam, and some of thetin-mercury amalgam will be present without any zinc in it at first,this being on the top surface of the coating. However, if thetin-mercury amalgam is left in contact with the zinc coating fortwenty-four hours or more, and an excessive amount of the tin-mercuryamalgam is not'used, suflicient of the mercury will amalgamate with thezinc that all of the zinc will become amalgamated with mercury, and theresulting coating will be a tin-zinc-mercury amalgam, from the outersurface thereof to at least the ferrous zinc alloy at the surface of themetal of the sheet. Due to the fact that the zinc requires a much largeramount of mercury to be amalgamated with the same to produce a softputty-like amalgam, than does the tin, this amalgamation of the mercurywith the zinc, when completed,

causes the coating to have a hard character, similar to that of thezinc, instead of a soft putty-like character, such as the tin-mercuryamalgam had before it was applied to the sheet.

The application of the putty-like tin-mercury amalgam to the sheet thathas previously been galvanized results in the dissolving of the zinc onthe sheet in the mercury of the tin-mercury amalgam, but the resultingliquefaction of the coating material on the sheet takes place throughthe thickness of the zinc coating thereon at such a slow rate that thestructure of the zinc coating on the sheet is not altered, although thecomposition changes from substantially pure 'zinc to a zinc-tin mercuryamalgam as the amalgamating process proceeds through tlie\coating. As aresult the characteristic spangles of the galvanized sheet remain afterthe amalg mation is completed, the sheet having substan ially the sameappearance two or three days,after the amalgam has been applied theretoas it had before any application of amalgam was made thereto.

When a putty-like amalgam containing 40% tin and 60% mercury by weightis utilized for application to a galvanized sheet that has a coatingthereon of zinc that amounts to one ounce per square running foot, orone-half ounce per square foot surface on each side of the sheet, theamalgam resulting will contain approximately 65.8% zinc, 13.7% tin, and20.5% mercury. With heavier coatings of zinc the percentage of zincwill, of course, be higher, and of course, the percentage of tin will beless where an amalgam containing a larger percentage of mercury isutilized. Galvanized sheets with coatings as heavy as two and one-halfounces per running foot are manufactured, and if the 10 above mentionedamalgam is-applied to such a heavily galvanized sheet, an amalgamcoating containing 79.2% zinc, 8.3% tin, and 12.5% mercury will result.As in all cases the amount of zinc in the amalgam will be over 50%, thecoating will not lose the characteristics of a zinc coating completely,but will be modified in its corrosion resisting characteristics to aconsiderable extent by the mercury contained therein, and to a lesserextent by the tin contained therein.

desired results obtained. As the putty-like amalgam is added to thecoating on the sheet, none of the zinc is lost, but the tin and mercuryis added thereto.

What I claim is:

1. A fabricated steel sheet having a zinc galvanizing coating thereon,said zinc coating having interruptions therein, and a coating of amercury amalgam over and adjacent the interruptions in said zinccoating, said amalgam including zinc, mercury and another metal thatfreely dissolves in mercury, containing a much greater proportion ofzinc than either mercury or said other metal and extending to theexposed surface of said coating and having at least as great aproportion of mercury therein at its exposed surface as adjacent themetal of the sheet.

2. A fabricated galvanized metallic sheet having a coating thereon of anamalgam of zinc,tin and mercury, said coating having at least as great aproportion of mercury therein at its exposed surface as adjacent themetal of the sheet, said coating having in excess of 50% zinc therein.

3. A fabricated steel sheet having a zinc galvanizing coating thereon,said zinc coating having interruptions therein, and a coating of an amalgam that includes zinc, tin and mercury thereon" over and adjacenttheinterruptions in said zinc coating, said amalgam coating having atleast as great a proportion of mercury therein having a bend therein, anamalgam protective coating over and adjacent said bend, said amal-,

gam including zinc, mercury and tin, said amalgam coating having atleast as much mercury therein at the exposed surface thereof as adjacentthe metal of said sheet, and having more zinc than tin and mercurytherein.

' 6. In. a fabricated galvanized metallic sheet having a bend therein, azinc coating having an interruption therein on the outside of said bendH "on the other side thereof, said amalgam extending to the exposedsurface of said coating and having at least as great a proportion ofmercury therein at its exposed surface as adjacent the metal of saidsheet, said amalgam having in excess of zinc therein.

8. A fabricated galvanized metallic sheet having a bend therein, saidsheet having a coating of only zinc on the inside of said bend and acoating of an amalgam including zinc, mercury and another metal thatfreely dissolves in mercury on the other side of said sheet over andadjacent the outside of said bend, said amalgam extending to the exposedsurface of said coating and having at least as great a proportion ofmercury therein at its exposed surface as adjacent the metal of saidsheet, said amalgam having vin excess of 50% zinc therein.

9. A fabricated metallic sheet having a coating I thereon of an amalgamincluding from to 80% zinc by weight, tin and mercury, said coatinghaving at least as great a proportion of mercury at its exposed surfaceas adjacent the metal I 'least as great a proportion of mercury at itsexposed surface as adjacent the metal of the sheet.

11. A fabricated galvanized metallic sheet having a coating thereon ofan amalgam including from 9% to 26% mercury by weight, from 45% to asmuch tin as mercury by weight and in excess of 50% zinc by weight, saidcoating having at least as great a proportion of mercury at its exposedsurface as adjacent the metal of the sheet and having the spangledappearance of a sheet having a galvanized coating.

5:1 1:11 L. KO.

